Arthur B. McDonald
Encyclopedia
Arthur B. McDonald is a Canadian
physicist and the Director of Sudbury Neutrino Observatory Institute. He also holds Gordon and Patricia Gray Chair in Particle Astrophysics at Queen's University
in Kingston, Ontario
.
in 1964 and M.Sc. in Physics in 1965 from Dalhousie University
in Nova Scotia
. He completed his Ph.D. in Physics from the California Institute of Technology
.
from 1970 to 1982. He became professor of physics at Princeton University
from 1982 to 1989, leaving Princeton to join Queen's University
. He is currently the University Research Chair at Queen's University.
predict that neutrinos should be made in staggering numbers. Neutrino detectors on the Earth
have repeatedly seen less than expected neutrinos. Because neutrinos come in three varieties (electron, muon, and tau neutrinos) and because solar neutrino detectors have been primarily sensitive only to electron neutrinos, the preferred explanation over the years is that those "missing" neutrinos had changed, or oscillated, into a flavor for which the detectors had little or no sensitivity. And if a neutrino oscillates, according to the laws of quantum mechanics
, then it must have a mass.
In August 2001, a collaboration at the Sudbury Neutrino Observatory (SNO), a detector facility located 6,800 feet underground in a mine outside Sudbury, Ontario, which was led by Arthur B. McDonald, checked in with a direct observation suggesting that electron neutrinos from the Sun
really were oscillating into muon and tau neutrinos. SNO published its report in the August 13, 2001, issue of Physical Review Letters, and it is widely considered as a very important result. McDonald and Yoji Totsuka
were awarded the 2007 Benjamin Franklin Medal
in Physics "for discovering that the three known types of elementary particles called neutrinos change into one another when traveling over sufficiently long distances, and that neutrinos have mass".
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
physicist and the Director of Sudbury Neutrino Observatory Institute. He also holds Gordon and Patricia Gray Chair in Particle Astrophysics at Queen's University
Queen's University
Queen's University, , is a public research university located in Kingston, Ontario, Canada. Founded on 16 October 1841, the university pre-dates the founding of Canada by 26 years. Queen's holds more more than of land throughout Ontario as well as Herstmonceux Castle in East Sussex, England...
in Kingston, Ontario
Kingston, Ontario
Kingston, Ontario is a Canadian city located in Eastern Ontario where the St. Lawrence River flows out of Lake Ontario. Originally a First Nations settlement called "Katarowki," , growing European exploration in the 17th Century made it an important trading post...
.
Early life
McDonald graduated with a B.Sc. in PhysicsPhysics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
in 1964 and M.Sc. in Physics in 1965 from Dalhousie University
Dalhousie University
Dalhousie University is a public research university located in Halifax, Nova Scotia, Canada. The university comprises eleven faculties including Schulich School of Law and Dalhousie University Faculty of Medicine. It also includes the faculties of architecture, planning and engineering located at...
in Nova Scotia
Nova Scotia
Nova Scotia is one of Canada's three Maritime provinces and is the most populous province in Atlantic Canada. The name of the province is Latin for "New Scotland," but "Nova Scotia" is the recognized, English-language name of the province. The provincial capital is Halifax. Nova Scotia is the...
. He completed his Ph.D. in Physics from the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...
.
Academic career
McDonald worked as a research officer at the Chalk River Nuclear Laboratories northwest of OttawaOttawa
Ottawa is the capital of Canada, the second largest city in the Province of Ontario, and the fourth largest city in the country. The city is located on the south bank of the Ottawa River in the eastern portion of Southern Ontario...
from 1970 to 1982. He became professor of physics at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
from 1982 to 1989, leaving Princeton to join Queen's University
Queen's University
Queen's University, , is a public research university located in Kingston, Ontario, Canada. Founded on 16 October 1841, the university pre-dates the founding of Canada by 26 years. Queen's holds more more than of land throughout Ontario as well as Herstmonceux Castle in East Sussex, England...
. He is currently the University Research Chair at Queen's University.
Research
Physicists have been investigating whether neutrinos have mass or not. Since the late 1960s, experiments have hinted neutrino may have mass. Theoretical models of the SunSun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
predict that neutrinos should be made in staggering numbers. Neutrino detectors on the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
have repeatedly seen less than expected neutrinos. Because neutrinos come in three varieties (electron, muon, and tau neutrinos) and because solar neutrino detectors have been primarily sensitive only to electron neutrinos, the preferred explanation over the years is that those "missing" neutrinos had changed, or oscillated, into a flavor for which the detectors had little or no sensitivity. And if a neutrino oscillates, according to the laws of quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
, then it must have a mass.
In August 2001, a collaboration at the Sudbury Neutrino Observatory (SNO), a detector facility located 6,800 feet underground in a mine outside Sudbury, Ontario, which was led by Arthur B. McDonald, checked in with a direct observation suggesting that electron neutrinos from the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
really were oscillating into muon and tau neutrinos. SNO published its report in the August 13, 2001, issue of Physical Review Letters, and it is widely considered as a very important result. McDonald and Yoji Totsuka
Yoji Totsuka
was a Japanese physicist and Special University Professor, Emeritus, University of Tokyo. Totsuka died on July 10, 2008 from colorectal cancer.- Early life :...
were awarded the 2007 Benjamin Franklin Medal
Benjamin Franklin Medal (Franklin Institute)
The Benjamin Franklin Medal is a science and engineering award presented by the Franklin Institute, of Philadelphia, PA, USA.-Laureates:*1998 - Emmanuel Desurvire *1998 - Robert B. Laughlin *1998 - David N. Payne...
in Physics "for discovering that the three known types of elementary particles called neutrinos change into one another when traveling over sufficiently long distances, and that neutrinos have mass".